In a statement published on its Web site, the FAA said that two of the 48 files on the compromised server held the personal information of more than 45,000 individuals who were FAA employees and retirees as of the first week of February 2006.
"The server that was accessed was not connected to the operation of the air traffic control system or any other FAA operational system, and the FAA has no indication those systems have been compromised in any way," the agency said.
A law enforcement investigation is under way.
The agency said that it was moving to prevent similar incidents and that it has identified short-term and long-term actions to improve its ability to protect personal data. It's contacting affected current and former employees by mail.
An FAA spokesperson did not immediately respond to a request for further information.
During the first 11 days of February, there have been 15 publicly reported data breaches, according to Privacy Rights Clearinghouse, a nonprofit consumer advocacy group.
Last month, Heartland Payment Systems reported a data breach that has the potential to be one of the largest on record. The payment processor, which handles more than 100 million transactions per month, said it had found malware on its network. It did not, however, disclose the duration of the breach or the number of accounts affected.
A minor consolation for current and former FAA employees: In its 2009 Identity Fraud Survey Report, published Monday, Javelin Strategy & Research says that the average consumer cost of identity fraud declined by 31%, from $718 to $496 per incident, its lowest level since 2005.
Network Computing has published an independent analysis on how to survive data breach laws. Download the report here (registration required).